| 1928 FRANK Rail Crossing Signal Patent Print Art |
| 1928 ERICKSON Street Traffic Signal Design Patent 49410 |
| 1928 DELCO REMY CORP Sound Signal Patent Print |
| 1928 WERNER Railway Signal Apparatus Patent |
| 1928 SWARTWOUT Design Signal Lamp Casing Patent 49389 |
| 1928 GIROLAMO RAGUSA Automatic Signal Patent |
| 1928 TAYLOR Railroad Crossing Signal Patent |
| 1928 CLARK COOPER Pneumatic Signal Patent Print |
| 1928 ADLAKE CO Signal Lantern Patent Print Art |
| 1928 SPARKS WITHINGTON CO Signal Patent Print |
| 1928 WIDMYER ROBERT Signal Device Patent Print |
| 1928 WAGGAMAN Design Traffic Signal Casing Patent 49386 |
| 1928 GRAY Railway Crossing Signal Switch Patent |
| 1928 MILLER CHARLES Railway Signal Patent Print |
| 1928 BRADLEY Theft Signal Switch Patent Print |
| 1928 SAMUEL Aeroplane Flare Or Signal Patent |
| 1928 STEVENS JOHN Signal Patent Print Art |
| 1928 HANSON Signal For Automobiles Patent Print |
| 1928 HAMM WILLIAM Signal Lantern Patent Print |
| 1928 BUTTRON Traffic Signal Observer Patent |
| 1928 GOLOMBOWSKI Automobile Signal Switch Patent |
| 1928 WILLIAM Signal Art Print Patent |
| 1928 JOHN Traffic Signal Apparatus Patent Print |
| 1928 HAAS Signal Bracket WESTINGHOUSE Patent 49405 |
| 1928 BRITTON HYBARGER Signal Device Patent Print |
| 1928 EWALD C DIECKERHOFF Signal Patent Print Art |
| 1928 CRITCHFIELD ROBERT Sound Signal Patent |
| 1928 SPEAR FURMAN Train Signal Lamp Patent Print |
| 1928 JENNINGS NELSON Signal System Patent Print |
| 1928 JOHANN WICKELAND Railway Signal Patent |
| 1928 FRANCIS HOGG Signal Device Patent Print Art |